The gorosei have been some of the dumbest characters ever since the Nika retcon. However this may not be one of those cases, Saturn himself arrived near/on egghead for a reason. As he has commanding priority over Vegapunk himself over the Seraphim (according to what we know).
Yes in a perfect world, he would have loved to hear that York somehow managed with the Seraphim, especially since York is a vegapunk herself so she has an overwhelming advantage in this situation, she can poison the strawhats and fuck over the other satellites.
However, the fact that he is there himself, and he brought Kizaru with him in the first place, means he needed assurance. A major chunk of the rest of the forces are in response to a Yonkou crew being involved.